Nah I don't agree with this, if you're putting gold into a different class, it's your fault for putting it there, and you shouldn't just be able to change it with a couple thousand diamonds and a checkbook.

Suggestion..... create or add a card where we ca move class research from one class to another class. Provide the ability,out to move research already completed between the various classes (tank, air or cannon).
We can move them within a class via the R&D card, but not from one to the other. It would be great to be able to move them from one class to another.

they've never had sound so I'm confused by what your talking about, maybe go to settings and check all your audio settings and make sure that they are all working correctly, and then go into your own personal settings and check all of them.